Flexible nano- and microliter injections on a single liquid chromatography-mass spectrometry system: Minimizing sample preparation and maximizing linear dynamic range

By applying two different injection volumes, it was possible to double the linear dynamic range of a liquid chromatography - triple quadrupole mass spectrometry instrument. For the analysis of haloperidol in plasma, the linear dynamic range could be increased from 25-5,000 ng/mL to 25-1,000,000 ng/mL. Both 10 nL and 2 μL injection modes showed very similar accuracy and precision. Additionally, more than 1,000 direct injections of untreated plasma were successfully carried out using a nanoliter valve with no measurable effect on LC performance (retention time, peak width, column pressure and background signal).